A node device that has joined an ad-hoc network is able to form a network by performing transmission and reception of a hello frame with another node device. For example, a node A that belongs to a certain ad-hoc network generates a hello frame that includes the route information held by the node A and broadcasts it periodically. A node B that has received the hello frame compares the route information held by the node B and the information included in the hello frame, and acquires the route information which the node B does not hold from the hello frame.
If the number of node devices that are included in an ad-hoc network increases, the ad-hoc network may be divided into a plurality of clusters, as illustrated in FIG. 1. Black circles in FIG. 1 represent node devices. In the example of FIG. 1, the ad-hoc network is divided into clusters A to C. In FIG. 1, ranges which radio waves from each node device reach are represented by dashed lines. For example, radio waves from the node N1 reach the nodes N2 and N4, so the node N1 can send a frame to the nodes N2 and N4. A node device such as the node N1 that is located near a boundary at which a plurality of clusters are in contact with one another can access a node device included in an adjacent cluster. Accordingly, for example, if a communication route is formed between clusters as represented by double lines in FIG. 1, a node device included in the cluster A is capable of communicating with a node device in another cluster via any of the nodes N1 to N3. Likewise, a node device included in the cluster B is capable of communicating with a node device in another cluster via the nodes N4 to N7, and a node device included in the cluster C is capable of communicating with a node device included in another cluster via the nodes N8 to N11.
A network in which a plurality of mobile nodes are grouped into a plurality of mobile groups is known as a related art. An administrator statically sets one of the mobile nodes included in a mobile group as a group leader of the mobile group. The mobile group leader provides supervisory control of the mobile group.
As an example, the following patent document discloses a related art.
Patent Document 1: Japanese National Publication (Translated PCT Application) No. 2009-508434
The number of node devices capable of communicating with a node device in an adjacent cluster may increase with an increase in the number of node devices in an ad-hoc network. A node device that does not perform a communication between clusters transfers a frame destined for a node device in another cluster, to a node device capable of communicating with a node device in an adjacent cluster from among the node devices which belong to the same cluster as itself. Accordingly, for a node device that communicates with a node device in another cluster, the number of candidate destinations to which to transfer a frame increases as the number of node devices capable of communicating with a node device in an adjacent cluster increases. If there are a large number of node devices that may serve as a destination to which to transfer a frame, the node device performs processing to determine a destination to which to transfer a frame, which results in complexity of processing of transferring a frame. Further, if the routing processing is more complicated, the time for routing will be longer, and a delay could be caused.